The present invention generally concerns means for clamping a bearing assembly to an elongated shaft. More particularly, the invention relates to a bearing assembly which may be secured to a shaft utilizing an improved clamping collar.
Bearing assemblies, such as pillow blocks, are often designed to be quickly attached to a shaft. Typically, the bearing assembly is first slipped along the shaft to the desired position. Once there, the inner race of the bearing assembly is secured utilizing one of various clamping techniques.
A common clamping method involves the use of set screws radially threaded through an axial extension of the inner race. Such set screws directly engage the shaft, thus maintaining the bearing assembly firmly in position. Alternatively, an annular collar may be fitted over the axial extension such that threaded bores in the collar are in register with radial bores in the extension (which may or may not be threaded). Another common clamping technique utilizes an eccentric collar. Like methods utilizing set screws, eccentric collars provide a relatively high degree of clamping force.
An additional clamping method is disclosed in U.S. Pat. No. 3,276,828. This technique utilizes a split annular collar inserted over an inner race extension. In this case, the extension includes a number of circumferentially spaced axial slots which form respective clamping fingers. The collar includes a screw, which is used to tighten the clamping collar about the clamping fingers. As a result, the clamping fingers are pushed into locking engagement with the shaft.
Due to its design, the split collar, or "hose clamp", technique generally offers one or more of the following advantages over other clamping methods: less marring of the shaft, easy attachment and removal, greater concentricity of the bearing and the shaft, less fretting corrosion, less tendency to fracture the inner race extension, less distortion of the raceway and fewer set screws to loosen. A significant disadvantage of this technique, however, is that it provides substantially lower clamping forces than the set screw and eccentric collar techniques discussed above. As a result, it is been found unsuitable for many applications.
In an effort to provide sufficient clamping force while retaining some of the advantages of the clamping collar design, a "hybrid" shaft locking method has been developed. This method, which is disclosed in U.S. Pat. No. 4,403,814, utilizes an annular collar fitted over an inner race extension having four clamping fingers. A pair of clamping fingers are tightened to force a respective two of the clamping fingers into engagement with the shaft. Reaction by the collar then pulls the other two clamping fingers into shaft engagement. While generally providing greater clamping force than the "hose clamp" method, this design reintroduces some of the disadvantages of set screw techniques.